This is from New Ultimates #3 by Jeph Loeb and Frank Cho.
A flashback reveals that Valkyrie and the other Defenders were given their powers by Loki, who was pretending to be Gunnar Golmen (you know, the guy Loki pretended to be in Millar's Ultimates 2?).
Thor is in Valhalla with Hela. Last issue she she told him that she would let him go if he gave her a child. Now Thor wants her to let him go, but she says she can't; the only way someone can return to the land of the living is if another takes their place. Thor says he'll kill her then, and she turns around.
The thought bubbles are from Valkyrie, who's narrating the whole issue.
Valkyrie is under the control of the Enchantress and is battling the Ultimates when Hawkeye shoots Enchantress with an arrow, freeing her (Loki seems to want this, saying "Oh, yes" when Enchantress is shot).
Valkyrie attacks Loki, who knocks her sword out of her hands with Thor's hammer.